9,164 research outputs found
Spin-polarized states of nuclear matter
The equations of state of spin-polarized nuclear matter and pure neutron
matter are studied in the framework of the Brueckner-Hartree-Fock theory
including a three-body force. The energy per nucleon calculated
in the full range of spin polarization for symmetric nuclear matter
and pure neutron matter fulfills a parabolic law. In both cases the
spin-symmetry energy is calculated as a function of the baryonic density along
with the related quantities such as the magnetic susceptibility and the Landau
parameter . The main effect of the three-body force is to strongly reduce
the degenerate Fermi gas magnetic susceptibility even more than the value with
only two body force. The EOS is monotonically increasing with the density for
all spin-aligned configurations studied here so that no any signature is found
for a spontaneous transition to a ferromagnetic state.Comment: Contribution to GISELDA Meeting, 14-18 January, 2002 (Frascati), to
appear in World Scientific (Singapore
Su(3) Algebraic Structure of the Cuprate Superconductors Model based on the Analogy with Atomic Nuclei
A cuprate superconductor model based on the analogy with atomic nuclei was
shown by Iachello to have an structure. The mean-field approximation
Hamiltonian can be written as a linear function of the generators of
algebra. Using algebraic method, we derive the eigenvalues of the reduced
Hamiltonian beyond the subalgebras and of
algebra. In particular, by considering the coherence between s- and d-wave
pairs as perturbation, the effects of coherent term upon the energy spectrum
are investigated
Transport parameters in neutron stars from in-medium NN cross sections
We present a numerical study of shear viscosity and thermal conductivity of
symmetric nuclear matter, pure neutron matter and -stable nuclear
matter, in the framework of the Brueckner theory. The calculation of in-medium
cross sections and nucleon effective masses is performed with a consistent two
and three body interaction. The investigation covers a wide baryon density
range as requested in the applications to neutron stars. The results for the
transport coefficients in -stable nuclear matter are used to make
preliminary predictions on the damping time scales of non radial modes in
neutron stars
Landau parameters of nuclear matter in the spin and spin-isospin channels
The equation of state of spin and isospin polarized nuclear matter is
determined in the framework of the Brueckner theory including three-body
forces. The Landau parameters in the spin and spin-isospin sectors are derived
as a function of the baryonic density. The results are compared with the
Gamow-Teller collective modes. The relevance of and for neutron
stars is shortly discussed, including the magnetic susceptibility and the
neutron star cooling.Comment: 2 pages, 2 figures, RevTex4 forma
Spin- and isospin-polarized states of nuclear matter in the Dirac-Brueckner-Hartree-Fock model
Spin-polarized isospin asymmetric nuclear matter is studied within the
Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism,
we present and discuss the self-consistent single-particle potentials at
various levels of spin and isospin asymmetry. We then move to predictions of
the energy per particle, also under different conditions of isospin and spin
polarization. Comparison with the energy per particle in isospin symmetric or
asymmetric unpolarized nuclear matter shows no evidence for a phase transition
to a spin ordered state, neither ferromagnetic nor antiferromagnetic.Comment: 8 pages, 6 figure
Medium mass fragments production due to momentum dependent interactions
The role of system size and momentum dependent effects are analyzed in
multifragmenation by simulating symmetric reactions of Ca+Ca, Ni+Ni, Nb+Nb,
Xe+Xe, Er+Er, Au+Au, and U+U at incident energies between 50 MeV/nucleon and
1000 MeV/nucleon and over full impact parameter zones. Our detailed study
reveals that there exist a system size dependence when reaction is simulated
with momentum dependent interactions. This dependence exhibits a mass power law
behavior.Comment: 5 figure
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